Conventionally, there have been communication systems, which transmit video data to mobile terminals by streaming (for example, “W-CDMA MOBILE COMMUNICATIONS SYSTEM” edited by Keiji Tachikawa, p. 357-360, Maruzen, Jun. 25, 2001). For example, a communication system, which transmits video data by streaming shown in FIG. 1 has been used. In a communication system 401 shown in FIG. 1, a plurality of cameras 410 recording video data, and a streaming server 430 transmitting video data to a plurality of mobile terminals 440 by streaming, connect to a single virtual private network (hereafter, referred to as VPN) 420, and are connected to each other via the VPN 420. In the communication system 401, a camera 410 transmits video data to the streaming server 430 via the VPN 420. The streaming server 430 then obtains and transmits the video data transmitted from the camera 410 to a mobile terminal 440. According to such communication system 410, since the cameras 410 and the streaming server 430 connect to a single VPN 420, there is an advantage that security between the cameras 410 and the streaming server 430 can be ensured.
In the conventional communication system 401, the cameras 410 and the streaming server 430 exchange data through connection to a single VPN 420. As a result, the cameras 410 providing video data, the streaming server 430 obtaining and transmitting the video data to a terminal, and the VPN 420 must have a unified security policy and address architecture.
In addition, since the cameras 410 and the streaming server 430 connect to a single VPN 420, it is necessary to provide as many VPNs 420, each connecting between the cameras 410 providing video data and the streaming server 430 obtaining and transmitting the video data to a terminal, as the number of groups, each needing to ensure security between the cameras 410 and the streaming server 430. As a result, costs for constructing such VPN 420 may increase widely. More specifically, when there are numerous groups that need to ensure security, it is necessary to construct as many VPNs 420 as there are cameras 410 and the streaming server 430 to be connected thereto. As a result, costs have remarkably increased.
An object of the present invention is to provide a communication system, which has high security and can be constructed at low cost, where an information providing-side providing information data and an information transmitting-side transmitting the information data obtained from the information providing-side to a terminal can maintain their own unique security policy, and a transfer device used for the communication system.